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How to size a shipboard RO watermaker
Calculate production, reserve and installation requirements before comparing marine watermaker quotations.
HOSON WATER editorial ·
Estimate production from the voyage schedule
Add the water consumed by cabins, galley and service spaces on a busy sailing day. List any engine-room or process demand separately if it has a different water quality requirement. Then divide the required production by the realistic daily operating window. Shore water, tank capacity and generator availability change that window, so include them on the same worksheet.
A 25-ton-per-day nameplate equates to approximately 1.04 tons per hour if production is continuous across 24 hours under the stated rating conditions. If the unit can run only 16 hours per day, the same hourly output would deliver approximately 16.7 tons before allowances for flushing, interruptions and variations in feed conditions.
Design for water quality and physical access
Submit minimum seawater temperature, maximum salinity and intake conditions. Ask the supplier to model the duty point under the coldest expected feed. A general operating temperature range describes the unit’s envelope, while rated capacity depends on the design basis. Check whether post-treatment, monitoring and a separate storage or distribution scope are required.
Send vessel interfaces with the inquiry
Provide a general arrangement drawing, installation opening, available voltage and frequency, intake pressure, reject routing and a sketch of tank connections. Include the service clearance needed to remove a membrane or pump. These details let the vendor distinguish an available skid from a system that can be installed and maintained aboard the vessel.